A reset spring over type super high pressure fuel injector

Abstract

The utility model discloses a reset spring upper -placed type superhigh pressure oil atomizer, contain oil atomizer casing, control valve screw, reset spring, control valve coupling and needle valve coupling. The oil atomizer casing middle part step ladder middle hole and the oil nozzle seat surface form the pressure accumulation chamber, and the control valve coupling is in close proximity to needle valve coupling and constitutes the upper -placed coupling cavity structure and is placed in the pressure accumulation chamber. Control valve coupling has control valve sleeve, stem, chamber and inlet, outlet oil throttle hole, needle valve coupling contains needle valve sleeve and stem, and the both form the closed coupling cavity and the volume is less than or equal to 45mm 3 . Reset spring is established in control valve stem upper end spring chamber, and the spring chamber top has inlet oil throttle hole. Control valve stem upper end surface is the plane, and the lower end surface is the spherical surface, and forms the self -positioning adjusting structure with needle valve stem plane end. The oil atomizer has obtained the significant technical breakthrough in the leakproofness, oil injection pressure, precision, dynamic response and oil injection rate adjustment, can effectively reduce the oil consumption and the discharge, improves the engine power, provides the powerful support for the high -efficient, environmental protection operation of engine, and the market application prospect is broad, and the technical value is great.

Description

Technical Field

[0001] This utility model belongs to the field of fuel injection systems, specifically referring to injectors in common rail injection systems, and is particularly designed as a top-mounted, high-pressure injector with a return spring to meet the high-efficiency combustion requirements of China VI and Euro VI emission regulations. Background Technology

[0002] As a key component of modern internal combustion engine fuel injection technology, the performance of the common rail injection system directly determines whether the engine can meet increasingly stringent emission regulations. Within the common rail injection system, the injector is one of the core components, responsible for injecting high-pressure fuel into the engine cylinders at precise timing, duration, and quantity. It plays a crucial role in fuel atomization quality, air-fuel mixture formation, and the combustion process.

[0003] However, the mainstream common rail injectors currently used in China under high emission standards have significant shortcomings in terms of technical specifications. The maximum injection pressure of existing common rail injectors is typically limited to 2000 bar, and they generally employ a structural design with static leakage. More critically, in existing common rail injectors, a low-pressure chamber is formed between the injector assembly and the control valve assembly. According to fluid mechanics principles, the volumetric leakage of the assembly gap is directly proportional to the pressure difference, directly proportional to the cube of the gap between the assemblies, and inversely proportional to the guide length. Under this structure, when the injector fails to inject fuel, a series of problems detrimental to engine performance will occur.

[0004] On the one hand, fuel in the high-pressure chamber at the injector end leaks into the low-pressure chamber through the gap in the injector assembly. Simultaneously, high-pressure fuel in the control chamber also leaks into the low-pressure chamber through the gap in the control valve assembly. This fuel leakage significantly increases engine fuel consumption because the leaked fuel fails to participate in the combustion process, directly resulting in fuel waste. Furthermore, fuel leakage increases engine carbon emissions, which is detrimental to environmental protection and makes it difficult to meet the carbon emission reduction requirements of China VI and Euro VI emission regulations.

[0005] On the other hand, high-pressure fuel leakage at the gaps between the fuel injectors can also damage the injector components. Leaking high-pressure fuel accelerates wear on parts, shortens the lifespan of the injectors, and increases engine maintenance costs.

[0006] Due to the aforementioned problems, traditional common rail injectors can only reach a maximum injection pressure of 2000 bar, making them unreliable at higher pressures. Ultra-high pressure injection technology is crucial for improving fuel atomization quality, promoting more complete combustion, reducing emissions, and enhancing fuel economy. Therefore, developing a new type of injector that can solve the leakage problem of existing common rail injectors, increase injection pressure, and operate reliably has become an urgent need to meet China VI and Euro VI emission regulations and improve engine performance. Summary of the Invention

[0007] To address the problems existing in the prior art, this utility model provides a top-mounted return spring ultra-high pressure fuel injector. The injector's injection pressure can reach 2500-3000 bar, increasing the injection rate without increasing the nozzle area. The higher injection pressure and smaller orifice diameter facilitate fuel atomization and mixing, resulting in more complete combustion.

[0008] This utility model is implemented as follows: a top-mounted return spring ultra-high pressure injector includes an injector housing, a control valve screw, a return spring, a control valve assembly, and a needle valve assembly; the injector housing has a stepped central hole in the middle, which forms a pressure accumulator cavity with the nozzle seat surface; the key feature is that the control valve assembly forms a top-mounted coupling cavity structure close to the needle valve assembly, and both are placed in the pressure accumulator cavity; the control valve assembly includes a control valve sleeve, a control valve stem, a control cavity, an inlet throttling orifice, and an outlet throttling orifice; the needle valve assembly includes a needle valve sleeve and a needle valve stem; a sealed coupling cavity is formed between the control valve assembly and the needle valve assembly, with a volume ≤45mm³; the return spring is disposed in the spring chamber at the upper end of the control valve stem, and the top of the spring chamber has an inlet throttling orifice in the radial direction; the upper end surface of the control valve stem is flat, and the lower end surface is spherical; the upper end surface of the needle valve stem is flat, and it cooperates with the spherical surface to form a self-adjusting structure.

[0009] More preferably, the control valve stem is a short rod structure, with its control valve stem diameter > needle valve stem diameter, and the difference between the two diameters ≥ 0.3 mm; the inner diameter of the control valve sleeve is > the inner diameter of the needle valve sleeve, and the difference between the two diameters ≥ 0.3 mm.

[0010] More preferably, the guide gap between the control valve sleeve and the control valve stem is ≤8μm, and the guide length is ≥9mm; the guide gap between the needle valve sleeve and the needle valve stem is ≤10μm, and the guide length is ≥8mm.

[0011] More preferably, the diameter of the oil inlet throttling hole at the top of the spring chamber is ≥φ0.4.

[0012] More preferably, the lower end of the control valve sleeve is provided with a first sealing surface that seals with the needle valve sleeve, and the first sealing surface has a first chamfer at the junction with the small outer circle; the upper end of the needle valve sleeve is provided with a second sealing surface that seals with the control valve sleeve.

[0013] More preferably, the needle valve sleeve has a two-stage central hole: the upper end is a large-diameter hole connecting the coupling cavity, which has a second chamfer between it and the sealing surface; the lower end is a needle valve rod guide hole, which has a third chamfer at its lower end.

[0014] More preferably, the control valve screw presses the control valve sleeve so that it fits tightly against the inner end face of the injector housing.

[0015] More preferably, the lower end face of the needle valve sleeve is provided with a needle valve spring, and a fourth chamfer is provided at the junction of the lower end face of the needle valve sleeve and the outer circle.

[0016] More preferably, the upper end face of the control valve stem is provided with a fifth chamfer of ≤0.3mm.

[0017] A further preferred embodiment has a sixth chamfer of ≤0.5mm between the upper end face of the needle valve stem and the outer diameter.

[0018] The technical advantages of this invention are as follows: Compared with the traditional 2000bar common rail injector, the common rail injector of this invention has achieved significant improvements in several key performance indicators, and has the following outstanding technical advantages:

[0019] Superior sealing performance and energy-saving and emission-reduction advantages: Traditional 2000bar common rail injectors suffer from static leakage in the clearance of moving parts. This not only wastes fuel and increases fuel consumption, but also exacerbates carbon emissions. Furthermore, fuel leakage can cause wear on components, reducing injector reliability and lifespan. This patented injector innovatively employs a static leakage-free structural design, ensuring comprehensive injector sealing even under ultra-high pressure (2500bar - 3000bar) operating conditions, effectively preventing fuel leakage. This improvement directly reduces fuel consumption, decreases carbon emissions, actively responds to environmental protection requirements, and significantly improves injector reliability and lifespan, reducing engine maintenance costs.

[0020] Higher injection pressure and superior injection performance: Traditional two-stage common rail injectors can only reach a maximum injection pressure of 2000 bar, while the injector of this invention can easily reach 2500-3000 bar. This significant increase in injection pressure greatly enhances the injection rate, shortening the injection time. The faster injection rate and shorter injection time help the fuel mix more thoroughly with the air, achieving more efficient combustion, thereby improving engine power output and fuel economy.

[0021] Stable central accumulator chamber and precise injection control: Traditional common rail injectors typically employ a long and narrow fuel channel design. During injection, significant pressure fluctuations occur within these channels, leading to a decrease in the average effective injection pressure. Furthermore, variations in injection intervals during multiple injections can easily result in differences in injection quantity, affecting engine combustion stability and performance. In contrast, this injector features a large-volume central accumulator chamber. This unique design effectively reduces pressure fluctuations during injection, ensuring a stable average effective injection pressure while significantly improving the accuracy of multiple injections. Precise injection control contributes to a more stable combustion process, enhancing the smoothness and reliability of power output.

[0022] Optimized return spring structure and rapid dynamic response: This injector features an added return spring structure and a carefully optimized overall structural layout. Through this rational design, hydraulic interference is effectively eliminated, enabling the needle valve to respond quickly to control signals and achieve precise opening and closing actions. The rapid dynamic response allows the injector to operate more accurately according to the engine's fuel injection requirements, improving the timeliness and accuracy of fuel injection and further optimizing the engine's combustion process.

[0023] Innovative Coupling Cavity Structure and Flexible Fuel Injection Adjustment: The injector control section of this invention employs an innovative coupling cavity structure design. This structure enables flexible adjustment of the fuel injection rate, allowing for adjustments based on different combustion conditions. Through this flexible adjustment, the engine can achieve lower fuel consumption, fewer emissions, and higher power output under various operating conditions, further optimizing overall engine performance and meeting the stringent requirements of modern engines for high efficiency, environmental friendliness, and energy conservation.

[0024] In summary, the common rail injector of this utility model has achieved significant technological breakthroughs in sealing, injection pressure, injection accuracy, dynamic response, and injection rate regulation through a series of innovative designs. It provides strong support for the efficient and environmentally friendly operation of engines and has broad market application prospects and important technical value. Attached Figure Description

[0025] Figure 1 This is a drawing of the fuel injector assembly of this utility model;

[0026] Figure 2 This is a magnified view of a portion of the control section;

[0027] Figure 3 This is a magnified view of the position of the control valve assembly;

[0028] Figure 4 This is a magnified view of a portion of the coupling cavity. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this utility model.

[0030] Please see Figures 1 to 4A high-pressure fuel injector with a top-mounted return spring includes an injector housing 1, a control valve screw 2, a return spring 3, a control valve assembly 4, and a needle valve assembly 5. The injector housing 1 has a stepped central hole in its middle, forming a pressure accumulator chamber Q between the central hole and the nozzle seat surface. The control valve assembly 4 is positioned close to the needle valve assembly 5, forming a top-mounted coupling chamber structure, with both components housed within the pressure accumulator chamber Q. This structure offers significant technical advantages: because the components are completely arranged within the high-pressure fuel chamber Q of the injector housing 1, there is no pressure difference, eliminating static leakage between the components. Compared to traditional structures with static leakage, this avoids fuel consumption losses and accelerated wear of parts caused by high-pressure fuel leakage, effectively reducing engine fuel consumption and carbon emissions, while extending the injector's service life and lowering engine maintenance costs. Furthermore, the large volume of the pressure accumulator chamber Q helps reduce pressure loss and fluctuations during injection, improving the average effective injection pressure and the accuracy of multiple injections, thereby enhancing engine combustion efficiency and performance.

[0031] The control valve assembly 4 includes a control valve sleeve 41, a control valve stem 42, a control chamber K, an inlet throttle orifice 410, and an outlet throttle orifice 411; the needle valve assembly 5 includes a needle valve sleeve 51 and a needle valve stem 52; a sealed coupling cavity O is formed between the control valve assembly 4 and the needle valve assembly 5, with a volume ≤45mm³. The design of this coupling cavity O brings several technical advantages. According to fluid mechanics principles, the volumetric flow rate between the assemblies is directly proportional to the pressure difference, directly proportional to the cube of the gap value between the assemblies, and inversely proportional to the guide length. The 9mm guide length and the guide gap between the control valve sleeve 41 and the control valve stem 42 within 8μm provide a stable volumetric flow for the coupling cavity O, ensuring consistent cyclic pressure in each cycle of operation, thereby achieving overall fuel quantity cyclic stability, improving the accuracy and stability of the injector's fuel injection, and facilitating more precise fuel injection control and optimizing the combustion process.

[0032] The return spring 3 is disposed in the spring chamber 420 at the upper end of the control valve stem 42. The top of the spring chamber 420 has a radially arranged fuel inlet throttling orifice 410. When the injector is stationary, the combined force of the spring and hydraulic pressure presses the control valve stem 42 against the needle valve stem 52. When the injector closes, the return spring 3 plays a crucial role. Under the action of the spring force, the control valve stem 42 moves rapidly downwards, transmitting the force to the needle valve for rapid closure, thus improving the dynamic response speed of the injector. Simultaneously, the fuel inlet throttling orifice 410 at the top of the spring chamber 420 has a diameter ≥ φ0.4, ensuring that the spring chamber 420 is filled with fuel when the control valve stem 42 reaches the top dead center position. Under the action of the spring force and hydraulic pressure, this further accelerates the closure of the needle valve, further enhancing the dynamic response performance of the injector. This allows the engine to respond to injection commands more quickly and accurately, improving engine efficiency and performance.

[0033] The upper end face 422 of the control valve stem 42 is flat, and the lower end face 424 is spherical. The upper end face 521 of the needle valve stem 52 is flat, and together with the spherical surface, they form a self-aligning adjustment structure. This spherical-flat contact structure achieves self-aligning adjustment capability through a small gap, ensuring dynamic balance during control valve stem movement, preventing local overload, improving the reliability and stability of the injector, reducing the risk of component damage due to local overload, and extending the service life of the injector.

[0034] Further preferably, the control valve stem 42 is a short stem structure, with a control valve stem diameter 417 > a needle valve stem diameter 520, and the diameter difference between the two is ≥0.3mm; the inner diameter of the control valve sleeve 41 is > the inner diameter of the needle valve sleeve 51, and the diameter difference between the two is ≥0.3mm. This diameter difference design helps optimize the fluid flow and mechanical properties inside the injector, improves the injector's working efficiency and reliability, and enables the injector to better adapt to the working environment of ultra-high pressure injection.

[0035] More preferably, the guide clearance between the control valve sleeve 41 and the control valve rod 42 is ≤8μm, and the guide length is ≥9mm; the guide clearance between the needle valve sleeve 51 and the needle valve rod 52 is ≤10μm, and the guide length is ≥8mm. This reasonable guide clearance and guide length design ensures the stability and accuracy of the control valve rod 42 and the needle valve rod 52 during movement, reduces problems such as uneven fuel injection caused by movement deviations, improves the fuel injection quality of the injector, and facilitates more complete combustion in the engine, thus reducing emissions.

[0036] More preferably, the oil inlet throttling hole 410 provided at the top of the spring chamber 420 has a diameter ≥ φ0.4, and its positive effect on improving the dynamic response speed of the injector has been explained above.

[0037] More preferably, the lower end of the control valve sleeve 41 is provided with a first sealing surface 414 that seals with the needle valve sleeve 51, and a first chamfer 416 is provided at the junction of the sealing surface 414 and the small outer circle 415; the upper end of the needle valve sleeve 51 is provided with a second sealing surface 510 that seals with the control valve sleeve 41. This excellent sealing design ensures that the high-pressure fuel inside the injector will not leak, guaranteeing the stability and reliability of the injector's operation, and improving the engine's fuel economy and emission performance.

[0038] More preferably, the needle valve sleeve 51 has a two-stage central hole: the upper end is a large-diameter hole 512 connecting to the coupling cavity O, with a second chamfer 513 between it and the sealing surface 510; the lower end is a needle valve rod guide hole 514, with a third chamfer 515 at its lower end. This two-stage central hole structure and chamfer design effectively ensure that the needle valve rod does not jam during relative movement, improving the smoothness and reliability of the injector's operation and reducing injection failures caused by jamming.

[0039] In a further preferred embodiment, the control valve screw 2 presses against the control valve sleeve 41, making it fit tightly against the inner end face of the injector housing 1, ensuring high-pressure sealing between the two, preventing high-pressure fuel leakage, and improving the overall performance and reliability of the injector.

[0040] More preferably, the lower end face 511 of the needle valve sleeve 51 is provided with a needle valve spring 6, and a fourth chamfer 516 is provided at the junction of the lower end face 511 and the outer circle, which helps the needle valve rod to reset and move stably, and improves the fuel injection performance of the injector.

[0041] More preferably, the upper end face 422 of the control valve stem 42 is provided with a fifth chamfer 423 of ≤0.3mm, which reduces stress concentration and improves the strength and reliability of the control valve stem 42.

[0042] In a further preferred embodiment, a sixth chamfer 522 of ≤0.5mm is provided between the upper end face 521 of the needle valve rod and the outer diameter 520, which also reduces stress concentration, improves the strength and reliability of the needle valve rod 52, and extends the service life of the injector.

[0043] In summary, the new invention's top-mounted return spring ultra-high pressure injector, through its unique structural design, solves the problems of leakage, slow dynamic response, and inaccurate injection found in existing common rail injectors. It offers multiple technical benefits, including improved fuel economy, reduced emissions, extended service life, and enhanced operational reliability and stability, thus better meeting the requirements of China VI and Euro VI emission regulations for efficient engine combustion.

[0044] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A top-mounted return spring type ultra-high pressure injector, comprising an injector housing (1), a control valve screw (2), a return spring (3), a control valve assembly (4), and a needle valve assembly (5); the injector housing (1) has a stepped central hole in the middle, and the central hole forms a pressure accumulator (Q) between itself and the nozzle seat surface; characterized in that: The control valve assembly (4) forms an upper coupling cavity structure close to the needle valve assembly (5), and the two are placed together in the accumulator cavity (Q); The control valve assembly (4) includes a control valve sleeve (41), a control valve stem (42), a control cavity (K), an oil inlet throttle hole (410), and an oil outlet throttle hole (411); The needle valve assembly (5) includes a needle valve sleeve (51) and a needle valve stem (52); The control valve assembly (4) and the needle valve assembly (5) form a closed coupling cavity (O) with a volume ≤ 45 mm³; The reset spring (3) is set in the spring chamber (420) at the upper end of the control valve stem (42), and the top of the spring chamber (420) is provided with an oil inlet throttle hole (410) in the radial direction; The upper end face (422) of the control valve stem (42) is a plane, and the lower end face (424) of the control valve stem is a spherical surface; The upper end face (521) of the needle valve stem (52) is a plane, which cooperates with the spherical surface to form a self-adjusting structure.

2. The injector according to claim 1, characterized in that: The control valve stem (42) is a short rod structure, and its control valve stem diameter (417) is greater than the needle valve stem diameter (520), with a diameter difference of ≥0.3mm; the inner diameter of the control valve sleeve (41) is greater than the inner diameter of the needle valve sleeve (51), with a diameter difference of ≥0.3mm.

3. The injector according to claim 1, characterized in that: The guide gap between the control valve sleeve (41) and the control valve stem (42) is ≤8μm, and the guide length is ≥9mm; the guide gap between the needle valve sleeve (51) and the needle valve stem (52) is ≤10μm, and the guide length is ≥8mm.

4. The injector according to claim 1, characterized in that: The oil inlet throttling hole (410) provided at the top of the spring chamber (420) has a diameter ≥ φ0.

4.

5. The injector according to claim 1, characterized in that: The lower end of the control valve sleeve (41) is provided with a first sealing surface (414) that seals with the needle valve sleeve (51), and the first sealing surface (414) and the small outer circle (415) are provided with a first chamfer (416); the upper end of the needle valve sleeve (51) is provided with a second sealing surface (510) that seals with the control valve sleeve (41).

6. The injector according to claim 1, characterized in that: The needle valve sleeve (51) has two-stage central holes: the upper end is a large-diameter hole (512) that connects to the coupling cavity (O), and a second chamfer (513) is provided between it and the sealing surface (510); the lower end is a needle valve rod guide hole (514), and a third chamfer (515) is provided at its lower end.

7. The injector according to claim 1, characterized in that: The control valve screw (2) presses the control valve sleeve (41) so that it fits tightly against the inner end face of the injector housing (1).

8. The injector according to claim 1, characterized in that: The needle valve sleeve (51) has a needle valve spring (6) on its lower end face (511) and a fourth chamfer (516) at the junction of the lower end face (511) and the outer circle.

9. The injector according to claim 1, characterized in that: The upper end face (422) of the control valve stem is provided with a fifth chamfer (423) of ≤0.3mm.

10. The injector according to claim 1, characterized in that: A sixth chamfer (522) of ≤0.5mm is provided between the upper end face (521) of the needle valve stem and the outer diameter (520).

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